Dipartimento di Scienze Biomolecolari e Biotecnologie, Università degli Studi di Milano, 20133 Milan, Italy.
Plant Physiol. 2010 Mar;152(3):1320-34. doi: 10.1104/pp.109.150631. Epub 2009 Dec 23.
Bromodomain and Extra Terminal domain (BET) proteins are characterized by the presence of two types of domains, the bromodomain and the extra terminal domain. They bind to acetylated lysines present on histone tails and control gene transcription. They are also well known to play an important role in cell cycle regulation. In Arabidopsis (Arabidopsis thaliana), there are 12 BET genes; however, only two of them, IMBIBITION INDUCIBLE1 and GENERAL TRANSCRIPTION FACTOR GROUP E6 (GTE6), were functionally analyzed. We characterized GTE4 and show that gte4 mutant plants have some characteristic features of cell cycle mutants. Their size is reduced, and they have jagged leaves and a reduced number of cells in most organs. Moreover, cell size is considerably increased in the root, and, interestingly, the root quiescent center identity seems to be partially lost. Cell cycle analyses revealed that there is a delay in activation of the cell cycle during germination and a premature arrest of cell proliferation, with a switch from mitosis to endocycling, leading to a statistically significant increase in ploidy levels in the differentiated organs of gte4 plants. Our results point to a role of GTE4 in cell cycle regulation and specifically in the maintenance of the mitotic cell cycle.
溴结构域和末端外结构域（BET）蛋白的特征是存在两种类型的结构域，即溴结构域和末端外结构域。它们与组蛋白尾部上存在的乙酰化赖氨酸结合，并控制基因转录。它们在细胞周期调控中也起着重要作用。在拟南芥（Arabidopsis thaliana）中，有 12 个 BET 基因；然而，只有其中两个，即抑制诱导 1（IMBIBITION INDUCIBLE1）和一般转录因子组 E6（GENERAL TRANSCRIPTION FACTOR GROUP E6，GTE6），进行了功能分析。我们对 GTE4 进行了表征，并表明 gte4 突变体植物具有细胞周期突变体的一些特征。它们的大小减小，并且它们具有锯齿状的叶子和大多数器官中细胞数量减少。此外，根中的细胞大小显著增加，有趣的是，根静止中心的身份似乎部分丢失。细胞周期分析表明，在萌发过程中细胞周期的激活延迟，细胞增殖过早停止，从有丝分裂到内循环，导致 gte4 植物分化器官的倍性水平显著增加。我们的结果表明 GTE4 在细胞周期调控中起作用，特别是在维持有丝分裂细胞周期中起作用。
